Genetics of Critical Care

The common patient interview question, “Has anyone in your family ever died of…?”, rarely, if ever, ends with a word like “sepsis” or “pneumonia”. The answer, however, may give ICU physicians new insight into successfully preventing and treating these fast-acting, often devastating conditions.

Image: Michelle Gong, MD

In worst cases, life-threatening insults such as sepsis, pneumonia, or trauma can progress to acute lung injury and acute respiratory distress syndrome (ALI/ARDS). This severe respiratory failure is characterized by intense inflammation and permeability of the endothelium (lung lining), allowing fluid into the lungs and lowering blood oxygen. ALI/ARDS cause an estimated 74,500 deaths in U.S. hospital intensive care units (ICUs) each year (more than the combined number of deaths caused by HIV, asthma, and breast cancer). These conditions tend to develop rapidly (within hours to days of the injury), and currently no effective drug treatment is available.

Years of treating critically ill patients began to reveal unusual trends to Michelle Gong, MD, Chief of Critical Care Research (Critical Care Medicine). Some young, otherwise healthy patients developed sepsis and organ failure; other presumably high-risk patients (those who were older, obese, or had heart failure, for example) recovered with few complications. Could other forces be at work?

Pursuit of an answer led Gong into genetic epidemiology, an emerging discipline that seeks to determine how a population’s genetic makeup and interaction with the environment influences a disease or its outcome. “A better awareness of genetic contributors will give us new insights into what might prevent or treat devastating illnesses,” she said.

Gong’s studies use the candidate-gene approach, focusing on specific genes thought to be biologically important in the development and progression of ALI/ARDS. “We used to think of sepsis as an unfortunate consequence of delayed treatment or poor health,” Gong said. “Understanding how genetic variation influences the way people respond to severe infection may help us identify high-risk patients and take preventive measures, similar to what is currently done for cancer or diabetes.”

Clinical application of this research could include such information being included in medical records or even on an encrypted microchip worn by the patient, which could help physicians assess the risk of organ failures and decide on the optimal management for the patient. This type of personalized medicine is the ultimate goal behind research of genetic influences on diseases and health.

The stressful conditions of a hospital ICU combined with the narrow window of treatment time for ALI/ARDS, themselves inherently unanticipated conditions, make studies like these difficult to conduct. And while there does appear to be genetic susceptibility to severe critical illnesses, environmental influence still plays a significant role.

“The importance of conditions like sepsis and ARDS are underestimated—these developments are often what actually kill people with chronic conditions like diabetes and heart disease,” said Gong. “From a public health standpoint, a clearer understanding of contributing factors will enable better preventive measures, which will benefit all high-risk groups.”